Cam-controlled knife for surgical instrument

Abstract

A surgical instrument may include a knife moveable from a stowed position completely within said surgical instrument to a cutting position in which at least part of the knife is positioned outside the surgical instrument. The surgical instrument may also include at least two cam slots, a cam pin extending from the knife into the cam slots, at least two guide slots that are substantially linear and are spaced apart from said cam slots, and a guide pin extending from the knife into the guide slots. In some embodiments, the cam slots are shaped to cause the knife to move from the stowed position to the cutting position as the knife is urged proximally.

1. Apparatus, comprising:
 a surgical staple holder; 
 a knife held by and movable relative to said staple holder, at least in part by rotation, from a stowed position completely within said staple holder to a cutting position in which a cutting edge of said knife is exposed outside said staple holder; 
 an anvil coupled to said staple holder, wherein said knife is movable upward out of said staple holder and toward said anvil from said stowed position; 
 at least two cam slots defined in said staple holder; and 
 at least one pin fixed to said knife that engages the at least two cam slots, wherein each of said cam slots includes two generally-parallel and spaced apart linear segments connected by a ramp segment angled relative to said linear segments, such that contact between said cam pin and each ramp causes upward motion of said knife. 
 
     
     
       2. Apparatus, comprising:
 a surgical instrument; 
 a knife moveable from a stowed position completely within said surgical instrument to a cutting position in which at least part of said knife is positioned outside said surgical instrument; 
 at least two cam slots defined in said surgical instrument; a cam pin extending from said knife into said at least two cam slots; 
 at least two guide slots defined in said surgical instrument, where said guide slots are substantially linear and are spaced apart from said cam slots; and 
 a guide pin extending from said knife into said at least two guide slots, 
 wherein said cam slots are shaped to cause said knife to move from said stowed position to said cutting position as said knife is urged proximally, wherein each of said cam slots includes two generally-parallel and spaced apart linear segments connected by a ramp segment angled relative to said linear segments, such that contact between said cam pin and each ramp causes upward motion of said knife. 
 
     
     
       3. The apparatus of  claim 2 , wherein proximal motion of said knife causes said cam pin to ride upward on said ramps, thereby causing said guide pin to rotate within said guide slots, wherein said knife rotates upward toward said cutting position. 
     
     
       4. The apparatus of  claim 2 , wherein said cam slots are shaped to cause said knife to move from said cutting position to said stowed position as said knife is urged distally. 
     
     
       5. Apparatus, comprising:
 a surgical knife having a first pin and a second pin extending laterally therefrom; 
 a cam slot on each lateral side of said knife, wherein said first pin extends into said cam slots; 
 a guide slot on each lateral side of said knife, wherein said second pin extends into said guide slots; wherein said guide slots are substantially linear and are located above said cam slots; 
 wherein said knife is slidable in a linear direction substantially parallel to said guide slots, and wherein said guide slots substantially constrain said first pin against motion substantially perpendicular to said linear direction; and 
 wherein said cam slots are shaped such that sliding of said knife along said linear direction urges said first pin in a direction that has a component of motion substantially perpendicular to said linear direction, and as a result said knife rotates about said second pin. 
 
     
     
       6. The apparatus of  claim 5 , wherein the proximal end of each said cam slot is located closer to said guide slot on the same lateral side of said knife than the distal end of each said cam slot. 
     
     
       7. The apparatus of  claim 5 , wherein each said cam slot includes two generally-parallel and spaced apart linear segments connected by a ramp segment angled relative to said linear segments, wherein the linear segment at the proximal end of each said cam slot is located closer to said guide slot on the same lateral side of said knife than the linear segment at the distal end of each said cam slot.